A supply house such as johnstone. Take all information of the furnace and old orifice with you and show them what you need.
Change out the gas flow orifice size to propane and adjust the gas valve.
its in the pilot lamp.. you need to slide the orifice out of there to clean or replace every so often
The manifold if the metal tube that directs the gas from the gas valve to (2-10) orifices so each orifice receives the same amount of pressure. This manifold is factory made and should never be changed.
A Natural Gas Orifice is Larger.
an electric furnace runs off of 208/230 Volts while a typical gas furnace runs off of 120 also a gas furnace will have a valve for the gas relay where the gas enters the furnace.
Remove the pilot assembly from the furnace and clean it up. You need to be careful when putting it back on at the gas valve so as not to crossthread the screw. Take a thin wire and clean the pilot orifice, then use a brush or sandpaper on the thermocouple.
Yellow flames from a natural gas furnace indicate that the combustion ratio is off and you have too much excess air in the mixture, if the discolored flame is isolated in the burner meaning on only 1 out of 3 or more then the burner/orifice may be out of alignment or there maybe a crack in the exchangers cell.
Defective thermocouple or possibly a dirty or clogged pilot orifice.
You can find a schematic for a gas furnace on the website, Uncionradio.
You should not run gas from the furnace to any appliances.
There are many places to find gas furnace prices. One can look on sites like Furnace Price Guides, Century Gas Furnace, and Consumer Reports. One can also find gas furnace prices by going to a local heating supply store.